Smoo Cave

Smoo is unusual in being formed two ways at once: the outer chamber was cut by the sea into Durness limestone, and the inner chambers were dissolved by fresh water from the Allt Smoo, which sinks into the ground upstream and reappears here. The entrance is about fifteen metres high and forty wide, the largest sea-cave entrance in Britain. Inside the first chamber, a walkway leads to a viewing point where the burn falls about twenty metres through a sinkhole in the roof into a pool, and beyond that a boat trip carries visitors into a further flooded chamber. Excavation has found Iron Age and Norse material at the entrance, which is dry, sheltered and obvious as a shelter. The name probably comes from the Norse smjuga, meaning a cleft.

What you actually see

• The entrance - fifteen metres high and forty wide, the largest of its kind in Britain.
• The roof waterfall - the burn dropping twenty metres through a sinkhole.
• The dual formation - sea-cut outer chamber and water-dissolved inner ones.
• The boat trip - a short passage into the flooded third chamber.

When to go

April to October for the boat trips, which do not run in winter or after heavy rain when water levels rise. The waterfall is most impressive after rain, which is also when the boats stop.

Honest expectations

The boat trips are weather dependent and cancel frequently; the outer chamber alone takes ten minutes to see. Access is down a long flight of steps. The cave is wet and the walkway slippery. Durness is remote with limited facilities.

Nearby

Durness and Balnakeil Beach are close; Cape Wrath is reached by ferry and minibus west.